Electrical Question

Prowarm underfloor heating. i noticed that one half of the floor was not heating! i have just tested the resistance and the 16 metre long mat is showing no resistance!! how can this happen and why??

I installed two 150W/m2 mats (one 20 metres long and the other 16 metres long) over 6mm insulation boards. Flexible screed over that and then 10mm natural slate over that using flexible adhesive. The mats were tested before, during (several times) and after tiling all giving the same resistance readings. The electrical connections were made and the underfloor heating worked brilliantly. That was 6 weeks ago, today I noticed that one half of the floor was not heating! I have just tested the resistance and the 16 metre long mat is showing no resistance!! How can this happen and why?? Can anybody give me any advice as to why it has taken 6 weeks to fail?? More to the point is there any way I can resolve the problem without ripping up a very expensive slate floor?? Really don't want £500 white elephant underfloor heating!! Thanks

2 Answers

Best Answer

If you have tested between the ends and it shows zero ohms resistance, this suggests that the element has a a short circuit. I would have thought that its more likely to have an infinate resistance as has actually gone open circuit (i.e. there is a break some where on the mat)

9 times out of 10 this is due to incorrect installation and or damage caused during installation,could have been just a slight nick that has got worse due to moisture getting in? but equally it could be just that the element has just gone faulty during use in the past few weeks.

Answered 15th Jan 2013

Electrical Safety Services

Member since 17 Oct 2011

The manufacturers should be able to send an engineer (warm-up certainly do), they use specialised heat/current seeking equipment that can identify the area of the break in wiring mat. Whilst they are quite expensive to call in (couple of hundred ish), at least they can identify the area of floor that has to come up, they will then repair the cable/mat and the can be floor re-laid. Not the cheapest, but better than starting again or having a half cold floor particularly in an area of the size you describe.

Answered 9th Apr 2013

S M Electrical Services

Member since 18 Jul 2010

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